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Posted by Darkarbiter on Sep-06-2008 16:58:

quote:
Originally posted by airwalker1
there is a diffrent sound for mp3 and wav for shure oversample for one but i think its best to make your tracks the best you can before coverting over to what ever format you think is best.i allways aim for 192kb and 16 bit wav any higher just sounds a bit to oversampled to me.

Fail.

Quit listening to eurodance. It's easily noticeable in pretty much any other genre.


Posted by Sanguis Mortuum on Sep-06-2008 23:23:

quote:
Originally posted by airwalker1
any higher just sounds a bit to oversampled to me.


Err, what?


Posted by kitphillips on Sep-07-2008 02:26:

This is why I'm so sick of these discussions. A bit too oversampled


Posted by 3F05Q on Sep-07-2008 09:11:

quote:
Originally posted by kitphillips
just totally confused about the relationship between song dynamics (lack thereof) and reduction of bitrate...


This is actually something that I haven't thought of until recently. On the entire subject... It depends mostly on what you're doing the listening with. The stuff I'm dealing with at work is amazing. I never believed the SACD hype, until I listened on some worthy speakers. I never thought I'd say, but there is a definately noticable difference between standard CD and SACD. Moving forward I decided to compare MP3s, and the difference is, again, quite noticible on REALLY good speakers.

Now, with all this talk of Nyquist Freq, I'm inclined to comment. For the sake of conversation, let's use nice round numbers. Let's say we have a "CD" sampling rate of 40kHz. At 20kHz (the Nyquist Frequency) we have a square wave. Now, that's assuming the phase of the recording is SPOT ON to the input... otherwise we get a 'beatnote'. Not important to be perfect at that high a frequency, but I think you see that at that frequency we have no dynamic definition at ALL. Anyway, what do we have at 10kHz? ONE sample per QUARTER wavelength. No dynamics there. 5kHz... two samples per quarter wavelength. Better, but depending on the phase of the analog wav being recorded, it can make a huge difference in the way the waveform is reproduced. So, yeah, bitrate can have a big affect on dynamics.


Posted by kitphillips on Sep-07-2008 09:37:

quote:
Originally posted by 3F05Q
This is actually something that I haven't thought of until recently. On the entire subject... It depends mostly on what you're doing the listening with. The stuff I'm dealing with at work is amazing. I never believed the SACD hype, until I listened on some worthy speakers. I never thought I'd say, but there is a definately noticable difference between standard CD and SACD. Moving forward I decided to compare MP3s, and the difference is, again, quite noticible on REALLY good speakers.

Now, with all this talk of Nyquist Freq, I'm inclined to comment. For the sake of conversation, let's use nice round numbers. Let's say we have a "CD" sampling rate of 40kHz. At 20kHz (the Nyquist Frequency) we have a square wave. Now, that's assuming the phase of the recording is SPOT ON to the input... otherwise we get a 'beatnote'. Not important to be perfect at that high a frequency, but I think you see that at that frequency we have no dynamic definition at ALL. Anyway, what do we have at 10kHz? ONE sample per QUARTER wavelength. No dynamics there. 5kHz... two samples per quarter wavelength. Better, but depending on the phase of the analog wav being recorded, it can make a huge difference in the way the waveform is reproduced. So, yeah, bitrate can have a big affect on dynamics.

Interesting idea... how does this interact with bit depth? If I have a 16 bit recording, doesn't that imply that every sample is 16 bits deep? Regardless of frequency?


Posted by Vortex_SA on Sep-07-2008 09:47:

quote:
Originally posted by 3F05Q
This is actually something that I haven't thought of until recently. On the entire subject... It depends mostly on what you're doing the listening with. The stuff I'm dealing with at work is amazing. I never believed the SACD hype, until I listened on some worthy speakers. I never thought I'd say, but there is a definately noticable difference between standard CD and SACD. Moving forward I decided to compare MP3s, and the difference is, again, quite noticible on REALLY good speakers.

Now, with all this talk of Nyquist Freq, I'm inclined to comment. For the sake of conversation, let's use nice round numbers. Let's say we have a "CD" sampling rate of 40kHz. At 20kHz (the Nyquist Frequency) we have a square wave. Now, that's assuming the phase of the recording is SPOT ON to the input... otherwise we get a 'beatnote'. Not important to be perfect at that high a frequency, but I think you see that at that frequency we have no dynamic definition at ALL. Anyway, what do we have at 10kHz? ONE sample per QUARTER wavelength. No dynamics there. 5kHz... two samples per quarter wavelength. Better, but depending on the phase of the analog wav being recorded, it can make a huge difference in the way the waveform is reproduced. So, yeah, bitrate can have a big affect on dynamics.


all this is nice and neat, but i think the dynamics everyone is talking about here is musical dynamics such as in "breakdowns" or "drops" or whatever you call it, isnt it so?

and i really think with all the respect i give to analog formats and WAVs that in a club, drunk, sometime just talking to a girl even the audiophiles there wouldn't notice a difference, and thats all there is to me, after all i wont be playing in a studio ill play in a club or a pub or whatever... not the most acoustically treated venue you know


Posted by Sanguis Mortuum on Sep-07-2008 11:13:

quote:
Originally posted by 3F05Q
At 20kHz (the Nyquist Frequency) we have a square wave. Now, that's assuming the phase of the recording is SPOT ON to the input... otherwise we get a 'beatnote'. Not important to be perfect at that high a frequency, but I think you see that at that frequency we have no dynamic definition at ALL. Anyway, what do we have at 10kHz? ONE sample per QUARTER wavelength. No dynamics there. 5kHz... two samples per quarter wavelength.


Oh dear, you really don't know what you're talking about do you...


Posted by kitphillips on Sep-07-2008 11:32:

quote:
Originally posted by Sanguis Mortuum
Oh dear, you really don't know what you're talking about do you...


Is this your reaction to everything? One might get the impression your a little arrogant hey?


Posted by Sanguis Mortuum on Sep-07-2008 11:45:

quote:
Originally posted by kitphillips
Is this your reaction to everything? One might get the impression your a little arrogant hey?
Its only my reaction when the person Im reacting to doesnt know what they're talking about.


Posted by Vortex_SA on Sep-07-2008 11:47:

quote:
Originally posted by Sanguis Mortuum
Its only my reaction when the person Im reacting to doesnt know what they're talking about.


explain, in detail, otherwise both of those posts are worthless.


Posted by Sanguis Mortuum on Sep-07-2008 12:07:

quote:
Originally posted by Vortex_SA
explain, in detail, otherwise both of those posts are worthless.

'Dynamics' is differences in volume, and volume resolution is determined by the bit-depth. Saying that sample-rate has any effect on dynamics is completely meaningless.

He also is trying to say that only having two samples per cycle up at 20khz makes a square wave, when everyone knows that DA converters always interpolate the samples to create a sine (using the Whittaker�Shannon interpolation formula), and that the Nyquist�Shannon sampling theorem guarantees that bandlimited signals (i.e. signals which have a maximum frequency) can be reconstructed perfectly from their sampled version, if the sampling rate is more than twice the maximum frequency. Only at frequencies above the nyquist does aliasing occur.

(All it would take is a cursory look at the wikipedia page on sampling to educate yourself in these matters, but I guess thats too much to ask of some people)


Posted by Vortex_SA on Sep-07-2008 12:13:

quote:
Originally posted by Sanguis Mortuum
'Dynamics' is differences in volume, and volume resolution is determined by the bit-depth. Saying that sample-rate has any effect on dynamics is completely meaningless.

He also is trying to say that only having two samples per cycle up at 20khz makes a square wave, when everyone knows that DA converters always interpolate the samples to create a sine (using the Whittaker�Shannon interpolation formula), and that the Nyquist�Shannon sampling theorem guarantees that bandlimited signals (i.e. signals which have a maximum frequency) can be reconstructed perfectly from their sampled version, if the sampling rate is more than twice the maximum frequency. Only at frequencies above the nyquist does aliasing occur.

(All it would take is a cursory look at the wikipedia page on sampling to educate yourself in these matters, but I guess thats too much to ask of some people)


that is a nice explanation right there i lower my hat (is that the right term?), nice to know this, and i read about mp3 compression quite a bit and understood it also is reconstructed from a stripped down wave... anyway i dont really care that much about it as i said earlier as long as it sounds good to me... but for the technical aspects its interesting to know...


Posted by kitphillips on Sep-07-2008 12:20:

Thumbs down

Well I've taken a close look at the Wiki pages on audio stuff, but didn't find that information. So thanks for sharing that with us, and next time try to be less arrogant and do it without making us attack you, you could have offerered something more helpful than
quote:
Oh dear, you really don't know what you're talking about do you...


Posted by DigiNut on Sep-07-2008 14:52:

There are two kinds of double-blind test in the industry for this sort of thing:

1. A/B, where the listener is given two samples, not told which is which, and either asked which one he prefers or asked to identify which is the original and which is compressed.

2. A/B/X, where the listener is given samples of both the original and compressed forms, is told which is which, and then given a 3rd sample ("X"), and asked to identify which of the original two samples it corresponds to (it's always a copy of one or the other).

The great thing about an A/B/X test is that the conclusion is not a qualitative one. In an A/B test, the listener might hear a difference but infer the wrong result; an A/B/X test clearly indicates whether or not the listener can even hear a difference.

A lot of trials have been done with respect to MP3. You can even do an A/B/X test online, where people can listen on their own equipment and thereby eliminate all the standard belly-aching, if you can trust that your test subjects won't cheat and put it through a spectrum analyzer. I don't have a bunch of bookmarks to give people because I honestly never thought it to be that interesting or important, but I'll state in no uncertain terms what I remember the results to be:

- No one was able to correctly identify a statistically significant number of MP3s at 320 kbps, in either an A/B or A/B/X test.
- Very few people (less than 1% of the test takers) could identify the 256 kbps MP3s.
- Some people could tell the difference at 192 kbps. Percentages would vary on each test (obviously), but results seemed to indicate that the typical, casual listener would not notice the difference, even on hi-fi equipment. The people who noticed were people who were trained to hear MP3 artifacts.
- Most people could tell at 128 kbps. No surprises there. If I recall correctly, the number usually weighed in at over 50% (some tests didn't even bother with 128 kbps because they deemed it a moot point).

I admit, I'm pulling this from memory and don't have a hard link for anyone, but if you're in doubt, try it. Burn 3 tracks to a CD for an A/B/X test and get 20 of your friends to listen. Make it short, no more than 30 seconds to a minute, otherwise you have to worry about listener fatigue.

Nobody - and I mean nobody - has ever proven to me personally that they can correctly weed out a high-bitrate MP3. And I've heard that claim from a lot of audio nuts. They're usually the same people buying $300-per-foot cables and $2500 power stations.

The standard caveat of course is that if it's for a label or you're expecting some sort of post-processing to be done, don't use MP3, simply because it is a lossy algorithm and the loss is cumulative over successive re-encodings.


Posted by Fledz on Sep-07-2008 15:34:

^^^I've done similar tests with friends when at my house and they could never tell the difference.

I should point out that I have Dynaudio BM5a's so it's not like we're not dealing with some damn good equipment here.


Posted by 3F05Q on Sep-07-2008 21:36:

First off... my original post was solely for the sake of kitphillips and really didn't have much to do with the original point of the OP's question. Heck, I'm perfectly content to listen to 128 MP3s all day long. If I'm in the mood to listen to a really good quality recording with a good system, then I wouldn't settle for MP3s of any bitrate. How often does that happen? Not often at ALL.... so MP3s it is most of the time.

quote:
Originally posted by kitphillips
just totally confused about the relationship between song dynamics (lack thereof) and reduction of bitrate...


So I gave a small explanation

But then I read this...

quote:
Originally posted by Sanguis Mortuum
Oh dear, you really don't know what you're talking about do you...


No, YOU don't know what I'm talking about, and that hurts you for some reason.

I know what I'm talking about, and I know what YOU are talking about. You are right to cite the Nyquist-Shannon Sampling Theorem, but I think you'll find my original statement is true, and I'll prove it. I'm discussing D to A, mostly, but in a bit I'll show you where the theorem falls on its face.

quote:
Wikipedia: Nyquist�Shannon sampling theorem
* In practice, neither of the two statements of the sampling theorem described above can be completely satisfied, and neither can the reconstruction formula be precisely implemented..... .....Practical digital-to-analog converters produce neither scaled and delayed sinc functions nor ideal impulses (that if ideally low-pass filtered would yield the original signal), but a sequence of scaled and delayed rectangular pulses. This practical piecewise-constant output can be modeled as a zero-order hold filter driven by the sequence of scaled and delayed dirac impulses referred to in the mathematical basis section below. A shaping filter is sometimes used after the DAC with zero-order hold to make a better overall approximation.

* Furthermore, in practice, a signal can never be perfectly bandlimited, since ideal "brick-wall" filters cannot be realized. All practical filters can only attenuate frequencies outside a certain range, not remove them entirely. In addition to this, a "time-limited" signal can never be bandlimited. This means that even if an ideal reconstruction could be made, the reconstructed signal would not be exactly the original signal. The error that corresponds to the failure of bandlimitation is referred to as aliasing.

* The sampling theorem does not say what happens when the conditions and procedures are not exactly met, but its proof suggests an analytical framework in which the non-ideality can be studied. A designer of a system that deals with sampling and reconstruction processes needs a thorough understanding of the signal to be sampled, in particular its frequency content, the sampling frequency, how the signal is reconstructed in terms of interpolation, and the requirement for the total reconstruction error, including aliasing and interpolation error. These properties and parameters may need to be carefully tuned in order to obtain a useful system.


Anyway...a little experimentation is in order:

Here is a 1kHz sin wave with constant amplitude converted to digital format with a sampling rate of 44.1kHz:



Looks good, right? A DAC would have no problem making that sound like a nice 1kHz tone to our ears. Also, there are enough samples per cycle to maintain that constant amplitude.

Let's look at a 5kHz sin wave with constant amplitude converted to digital format with a sampling rate of 441kHz:



What we are starting to see here is DYNAMICS being affected. Not much, that's true, and I fully expect, that by the N/S Samp Theorem we'd get a nice constant amplitude sine wave back out the other side IF this digital waveform goes UNTOUCHED by any compression or such.

Let's look at a 10kHz sin wave under the SAME conditions:



Again, the N/S Samp Theorem will probably be able to recreate this one, but we can see that the dynamics for us in the digital processing are DEFINATELY affected.

Now let's see how a quadrupling (sp?) of sample rate can help aleviate this behavior:

11kHz sin wav sampled at 44.1kHz at two zoom levels:





Now... what if we kept the frequency at 11kHz and multiplied the sampling frequency by FOUR? We'd get this:



See how the amplitude is maintained? We cannot help but to conclude that an increase in sampling frequency (preferably a large increase) will help to maintain the dynamics of a recording through ADC.

NOW... back to the wikipedia quote I have up there... you know, the one about how the theorem breaks down in practical use? Yeah...

So since the signal can never be perfectly bandlimited, we're going to get frequencies that are higher than or equal to the nyquist frequency. So let's take HALF of our sampling frequency (22050Hz) and sample it at 44.1kHz.

This diagram has 3 frequencies sampled: 22049Hz (for illustrative purposes), 22050Hz, and 2205Hz..



So we put a 22050Hz tone in, and what do we get? 2205Hz output through a DAC as a result of the phase of the input to the sampling frequency. No DAC on the planet would spit that digital waveform back out as 22050Hz. Even on my speakers it sounds as a 2205Hz tone, whereas the 22049 is inaudible as expected. This specific result is somethign I just stumbled upon and found interesting since it's a perfect example of the breakdown of the theorem.

(All it would take is a cursory experiment in a practical application to educate yourself in these matters, but I guess thats too much to ask of some people)


Posted by Vortex_SA on Sep-07-2008 23:40:

really interesting stuff right there really im always in for some knowledge,

but i don't get it, who has the biggest dick in the end?


Posted by 3F05Q on Sep-08-2008 00:22:

quote:
Originally posted by Vortex_SA
really interesting stuff right there really im always in for some knowledge,

but i don't get it, who has the biggest dick in the end?


Newton, I'd say.


Posted by Vortex_SA on Sep-08-2008 00:41:

quote:
Originally posted by 3F05Q
Newton, I'd say.


i think hawking wins by girth tho...


Posted by 3F05Q on Sep-08-2008 00:59:

quote:
Originally posted by Vortex_SA
i think hawking wins by girth tho...


Last 15 seconds or so:

http://www.jibjab.com/view/145602


Posted by Vortex_SA on Sep-08-2008 01:06:

quote:
Originally posted by 3F05Q
Last 15 seconds or so:

http://www.jibjab.com/view/145602


Family guy FTW...


Posted by thoughtlessjex on Sep-08-2008 01:20:

quote:
Originally posted by Darkarbiter I'd also like to point out (in theory anyway) that a 1440kbps mp3 would sound better then a 1440kbps wav. You would have to rip from an even better quality source though, like vinyl or whatever.

Huh? Okay, so first of all, the standard for wavs 44.1 kHz 16 bit. That means that every sample is 16 bits, and every second has 44,100 samples. This boils down to the standard "bitrate" for a wav file being 705.6 kbps. This is less than half the bitrate you're suggesting.

Second of all, I've heard people argue that the industry standard for wav files is arguably of better or near equal quality in comparison with most hifi record players (they have physical limitations in terms of dynamic contrast, stereo fidelity, and the width of the needle making certain frequencies indistinguishable). So a wav with twice as much fidelity would be pretty much the highest quality in an easy to record medium out there.

I can understand a 1440 kbps mp3 being better than a wave of the same bitrate, but even then, the quality at that point would be indistinguishable, and as has been said, is indistinguishable between a 44.1 kHz 16 bit wav and a 320 kbps mp3.


Posted by kitphillips on Sep-08-2008 02:50:

quote:
Originally posted by thoughtlessjex
Huh? Okay, so first of all, the standard for wavs 44.1 kHz 16 bit. That means that every sample is 16 bits, and every second has 44,100 samples. This boils down to the standard "bitrate" for a wav file being 705.6 kbps. This is less than half the bitrate you're suggesting.


Your forgetting its stereo mate I think maybe what hes trying to say is that MP3 is more selective about the frequencies it removes, meaning that you would hear the reduction in quality less because your not just chopping off everything above 20 Khz completely. I THINK thats what he's saying anyway.


Posted by Darkarbiter on Sep-08-2008 03:55:

I'm sure under at least 1% of circumstances I could tell the difference between a 192khz 24 bit wav and a 44.1khz 16 bit one, but more to the point the former would take up a shitload of space for minimal gain(ok I'm talking out my ass here, I don't think I've ever actually heard anything above cd quality). It's more a matter of where you draw the line, and IMO cd is def quite a fair bit better then 320kbps mp3, I dunno if I can identify it in a test, but when I hear the cd version after only hearing the 320kbps previously and go WOW, look at the extra depth of that whooshing sound/bass etc and enjoy it more because of it I know the extra space its taking is worth it.

Tests aren't what matters. Then again, I guess i guess if your playing at a club or whatever, and you only have a 40 gig hdd on your laptop its probably better to have the extra variety just incase rather then your songs sounding 5-10% better. For home listening though, I'm still very dissapointed if my favourite mix/cd not avaliable at a reasonable commercial price isn't avaliable in wav, as I'm missing out on that extra enjoyment and the hdd space/dl bandwidth is so worth it.


Posted by kitphillips on Sep-08-2008 08:21:

So now I've actually had a chance to read your post 3f05Q:
Its quite interesting what your saying, and works in theory, but I don't think its true because what seems to be being affected based on those diagrams isn't actually dynamics, but harmonic content. The wave which was originally a sine is being turned into a square - I understand this to be aliasing. So the idea is that with the Nyquist-Shannon formula, you can interpolate to create a perfect copy of the original wave upto the nyquist frequency, but above this the sound will be increasingly aliased, and the wave will look more like a square due to lack of samples to make up the high freq sine wave etc... So I'm not sure why you think dynmics will be affected exactly?
I guess I'm just saying, based on those diagrams, the wave has just as much vertical freedom no matter how much it gets squared by aliasing, so the amount of aliasing might change, but the actual volume won't, leading to equal dynamics across the whole range...
Interesting discussion now...


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